An in-vehicle navigation apparatus contributes to a user's efficient and safe operation. For instance, the apparatus detects a present position using GPS (Global Positioning System) etc. as the vehicle travels, and displays the detected present position on a road map. The apparatus further designates a optimum route from a departure point to a destination, and guides the vehicle along the guide route via a display device, audio output device, or the like.
The navigation apparatus has several functions other than a route guide function. For example, traffic regulation information about travel roads of the vehicle is acquired based on present positions; changes of traffic regulation information are informed a driver; a vehicle speed is controlled based on static information such as a speed limit or halt sign; and vehicle controls are varied based on dynamic information such as road surface conditions (refer to Patent document 1).                Patent document 1: JP-2005-173909 A        
Moreover, another navigation apparatus has a function to provide regulation information such as a speed limit using regulation data previously stored in memory as a map database when approaching or passing through a corresponding road.
In Patent document 1, traffic regulation information such as a speed limit is stored as follows: the information may be stored as a database to be associated with map data in an in-vehicle or detachable storage medium (e.g., CD-ROM, DVD-ROM); or the information as the database may be received from an outside of the vehicle via vehicle-to-vehicle communications or vehicle-to-road communications and appropriately updated using difference data received via the communications. In other words, the information as the database thus needs to be constantly updated to newest data.
For example, the updated regulation information may be temporarily valid for a predetermined validity period and be not updated again after the validity period expires. In this case, the vehicle speed is controlled based on the inappropriate regulation information.
Moreover, in a conventional in-vehicle navigation apparatus, if regulation information is changed, a user may manually change set points or values. However, when usual regulation information is changed temporarily because of road state changes due to weather or road construction, it is troublesome for a user to change set points to follow the changed information without fail. For instance, if the changed information is valid for a limited time period, cautious operations are needed. If the cautious operations are impossible, the original information is reluctantly maintained without being changed. The driver has no other choice to drive the vehicle according to actual traffic regulations.